1. Field of the Invention
The invention concerns a test device for analysing in particular a biological sample liquid comprising a composite body formed from several layers of flat material and at least one sample channel located in the composite body for transporting the sample liquid from a site of application to a measuring site. The invention also concerns a process for producing such a test device and preferred uses thereof.
2. Description of Related Art
An analytical disposable test element for determining an analyte in a liquid is known from WO 99/29429 which enables a spatial separation between the sample application site and the detection zone while using minimal sample volumes. A single channel capable of capillary liquid transport is provided for this purpose and the geometry of this channel is determined by an intermediate layer while a support and a cover made of a flat material provide a lower and upper boundary. It is essential for such diagnostic systems that the accuracy of the results measured by the system is ensured at all times. Poor maintenance of instruments, incorrect storage of reagents, test strips or system fluids, exceeding expiry dates or incorrect handling by the user are only some of the reasons which can lead to incorrect measuring results in practice. Hence controls are commonly used for the quality control of test carriers in which liquid reagents are applied to the test strip instead of sample material in order to generate measuring results that are within the specified target ranges. A disadvantage of this method is that the checked test carrier is consumed by this process and is no longer available for measuring the actual sample material. Hence this method only allows a random check of samples taken from a large number of test carriers.
In order to overcome this disadvantage U.S. Pat. No. 5,591,403 discloses the provision of several sample channels located in one plane which are all filled with the same sample liquid where at least one channel contains a control substance. A disadvantage of such planar channel geometries is that they are complicated and costly to manufacture. In particular it is difficult to integrate different reagents in channels that are in close proximity while strictly separating the individual processes.
Hence the object of the invention was to avoid the disadvantages of the prior art described above and to achieve a design which is technically more advantageous to manufacture and is also more compact which can also be used to carry out more complex test formats. An additional aim is to describe a simple manufacturing process for such test devices and test elements.